2016 This year, China's photovoltaic market experienced a major boom, with 34.54 GW of new installed capacity. , with a total installed capacity of 77.42 GW , both ranking first globally. Of course, the booming market hasn’t been without its challenges—risks such as low prices and rushed installations inevitably come along with it. As a result, quality issues in photovoltaic power plants have become a focal point of concern for stakeholders both within and outside the industry.

A photovoltaic power plant system consists of multiple components, including modules, inverters, combiner boxes, and mounting structures. Any issue in even one of these components can disrupt the plant's operation—ranging from minor losses in power generation to, in severe cases, causing a fire that wipes everything out. According to data compiled by the operations and maintenance company, equipment failures on the DC side—such as modules, inverters, and combiner boxes—account for as much as 90.18% of all reported issues. ; Faults in AC-side equipment such as cables, packaged substations, civil works, and step-up stations accounted for 9.82%. 。

3-15 At this juncture, the editor has specially compiled a list of common quality issues in photovoltaic power generation systems, dissecting the hidden risks lurking in each stage.

1. Photovoltaic Modules

Photovoltaic modules are critical equipment for power plant operation, accounting for 50% of the cost of a photovoltaic system. Look, issues with the components could severely undermine the power plant's profitability. Industry insiders point out that using photovoltaic modules whose quality isn't properly assured will likely put developers under immense financial strain down the road. This pressure will be at 5 It becomes apparent in about 10 years.

Frequently Asked Questions:

1. Hot Spot: In photovoltaic modules, a hot spot occurs when, under sunlight, certain cells are shaded and fail to generate electricity. This causes the shaded areas to heat up significantly more than the unshaded parts, leading to excessive temperatures and, in severe cases, irreversible damage in the form of dark, burnt-out spots.

When the hotspot effect reaches a certain level, the solder joints on the module melt and damage the grid lines, ultimately leading to the complete failure of the solar panel assembly. According to industry data, the hotspot effect reduces the actual lifespan of solar panel modules by at least 10%. %.

For a certain 40 MW Photovoltaic power station: On-site sampling of 2,000 units from the station A thermal hotspot test conducted on the photovoltaic modules revealed a significant number of hotspots caused by shading and inherent module quality issues, with the hotspot occurrence rate reaching 3%. Among these, dust accumulation and bird droppings causing hot spots account for approximately 1.3%, while component quality issues contribute to a hot-spot occurrence rate of around 1.7%.

When a module is shaded, it triggers the bypass protection device inside the junction box located behind it, causing currents as high as 9A to flow through the module string. A DC current of around ±100 will instantly be applied to the bypass device, causing 100 to generate within the junction box. Prolonged exposure to high temperatures has minimal short-term impact on both solar panels and junction boxes, but if shading persists over time without being addressed, it can significantly reduce the lifespan of both the junction boxes and the solar panels. Industry news reports frequently highlight cases where junction boxes have been damaged by overheating—often with shading identified as one of the primary culprits.

2. Hidden crack:

Hidden cracks refer to tiny fissures that appear within solar cells. These hidden cracks can accelerate power degradation in the cells, compromising the module's expected lifespan. Moreover, under mechanical stress, these cracks tend to propagate, potentially leading to open-circuit failures. Additionally, hidden cracks may also trigger the hot-spot effect, further reducing the efficiency and reliability of the solar panel.

Battery fragments (left photo), battery microcracks (right photo)

Battery fragments and hidden cracks are typically caused by external forces. Fragments are usually visible to the naked eye and can significantly impact the component's power output. Hidden cracks, on the other hand, are difficult to detect with the naked eye but still affect the component's performance to some extent—they can easily lead to hotspots, which may eventually develop into full-blown fragments.

3. Snail pattern:

Snail trails refer to the phenomenon where black or white linear patterns appear on the surface of solar cell units (the power-generating components). Because these patterns resemble the marks left behind after a snail has crawled across a surface, they are commonly known as "snail trails."

Cause: Primarily triggered by three conditions—crack formation, moisture penetration, and sunlight exposure.

Cracks have developed within the battery cells, allowing moisture to seep into the cracks through the resin backsheet and encapsulation materials. Once inside, the moisture reacts with the silver used to form the finger-shaped electrodes (thin electrodes) of the battery cell, causing silver ions to diffuse throughout the encapsulation material. Under these conditions, when sunlight shines on the solar panel, the silver ions chemically interact with additives present in the encapsulation material, leading to the formation of silver oxide and silver sulfide. As a result, black or white linear patterns emerge along the cracks.

Zhangjiakou Yangyuan 100 MW A large number of components at the power plant are showing snail-track patterns, including 70 MW units. Severe snail lines appear.

A resident in Europe noticed lightning-like patterns on their rooftop polycrystalline modules, 2013. Installed in 2014 Snail patterns appeared this year and have continued to increase and expand ever since. The components are sourced from a domestic manufacturer.

250 MW in the Shandong region Severe snail-marking has been observed on power plant components, and the supplier involved amounts to 20. Home

4. Power degradation:

Photovoltaic module power degradation refers to the gradual decline in the module's output power as exposure to sunlight increases over time. This power degradation in PV modules can generally be categorized into three types: first, degradation caused by destructive factors; second, the initial light-induced degradation of the module; and third, aging-related degradation due to long-term use.

According to data released by the Photovoltaic Industry Association, approximately one-third of the power plants already built in China are operational. Some components are substandard in quality, and another portion has already degraded by 25% over the past three years. The indicators that should naturally degrade over the years—even at some power plants, degradation can reach as high as 30% in the year of construction. Multiple issues have been identified: Testing conducted by the Jianheng Certification Center revealed that, in an 8MW photovoltaic power station in Xinjiang, out of 3,178 PV modules inspected via infrared imaging—2,856 units were sampled—19% exhibited signs of "虚焊" (cold solder joints), leading to hot-spot effects. Meanwhile, in a 10MW PV power station in Gansu, a random inspection found that as many as 58% of the PV modules showed significant power degradation.

5.PID The results of the 3rd national supervision and spot-check on the quality of grid-connected photovoltaic inverters involved 52 batches of products produced by 52 enterprises across 13 provinces (and municipalities). The inspection revealed that 6 batches failed to meet the relevant standards—specifically, 5 batches were found non-compliant in the "AC output-side over/undervoltage protection" category, while 2 batches failed to meet requirements in the "harmonics and waveform distortion" category.

(Potential Induced Degradation) ) Commonly known as potential-induced degradation.

Potential-Induced Degradation Effect (PID) Potential Induced Degradation ) occurs when the battery module is exposed to high voltage over an extended period, causing leakage current between the glass and encapsulation materials. This leads to a buildup of significant electrical charges on the surface of the solar cells, severely degrading the passivation effect and ultimately resulting in module performance falling below design specifications. PID When the phenomenon becomes severe, it can cause a power degradation of more than 50% in a single module, thereby affecting the overall power output of the entire string. Coastal regions characterized by high temperatures, high humidity, and high salinity/alkalinity are most susceptible to PID.

2. Photovoltaic Inverters

The photovoltaic inverter is the "brain" of a PV power plant, responsible for converting electricity from direct current to alternating current. If the inverter fails, it can disrupt the entire operation of the plant.

Frequently Asked Questions:

1. DC Arcing:

In the entire photovoltaic system, the DC-side voltage typically ranges from 600 to 1000V. , photovoltaic module connectors are highly susceptible to DC arcing due to loose connections, poor contact, moisture in the wiring, or insulation breakdown. DC arcing can cause a rapid increase in temperature at the contact points, and sustained arcs may generate temperatures as high as 3,000–7,000 High temperatures in ℃, accompanied by the high-temperature carbonization of surrounding components, can lead to blown fuses and damaged cables in minor cases, while in severe instances, they may cause components and equipment to catch fire.

2015 Year 3 The incident of an inverter spontaneously combusting at a photovoltaic power station in northwest China sent shockwaves through the industry. After investigating the northwest-based station, Wang Sicheng, a researcher at the Energy Research Institute of the National Development and Reform Commission and a board member of the Chinese Renewable Energy Society, revealed that 40% The power station fire was caused by DC arcing, with the photovoltaic inverters—responsible for converting DC electricity into AC—being directly affected.

2. Output side overcurrent Undervoltage Protection

So-called over/ Undervoltage protection primarily refers to significant fluctuations in grid voltage, with the range exceeding CQC. When the grid connection standards specify over- or undervoltage thresholds, the inverter must shut down and indicate the corresponding reason for the shutdown. Over/ Undervoltage protection is a key factor in determining whether an inverter meets quality standards. The main components of the CQC certification for inverters include EMC, safety, and grid connection—specifically, these three areas. Among them, over/undervoltage and over/underfrequency protections are critical aspects of grid-connection requirements. If these protective functions fail to meet standards, it could severely impact both the stability of the photovoltaic system and the overall distribution network.

3. Harmonics and Waveform Distortion

Inverters can cause grid disturbances, including harmonics. Grid disturbances refer to any phenomenon that alters the ideal sinusoidal waveform of voltage and current in terms of amplitude and frequency.

Harmonics can occur in every stage of electricity generation, transmission, and consumption, primarily originating from non-linear devices in the power grid and the growing number of power electronic systems. The danger posed by harmonic currents lies in their ability to create harmonic voltage drops across the grid's short-circuit impedance, thereby distorting the voltage waveform. User-side voltage = Infinite Grid Stabilizes Voltage Harmonic voltage drop).

2015 October of the year 27th of the month Today, the State Administration for Market Regulation announced the 2015 The results of the national supervision and spot-check on the quality of grid-connected photovoltaic inverters for the third quarter of the year revealed that 14 out of 55 batches—produced by 55 companies across 13 provinces and municipalities—failed to meet the required standards. The overall failure rate was 25.5%. Specifically, the nonconforming products were found to be deficient in areas such as rated input/output specifications, harmonic and waveform distortion, power factor, DC component levels, and over/under-voltage protection features.

2016 September 27th of the month On the same day, the State Administration for Market Regulation announced the 2016 The results of the 3rd national supervision and spot-check on the quality of grid-connected photovoltaic inverters involved 52 batches of products produced by 52 enterprises across 13 provinces (and municipalities). The inspection revealed that 6 batches failed to meet the relevant standards—specifically, 5 batches had不合格 in the "AC output-side over/undervoltage protection" category, while 2 batches were found non-compliant in the "harmonics and waveform distortion" category.

4. Island Effect

The so-called "islanding effect" occurs when a power generation unit connected to the public grid fails to detect, or lacks proper detection mechanisms for, a grid outage—and continues to feed electricity back into the grid despite the loss of external power. To ensure the safety of maintenance personnel, the grid must be equipped with an anti-islanding inverter. However, even this inverter has a tiny blind spot—typically around 0.1 percent. As a result, if this blind spot is triggered, the electricity generated by the photovoltaic power station could inadvertently flow into the busbar of the line being serviced, posing a serious threat to the lives of the technicians working on it.

5. Monitoring data is inaccurate.

The inverter's monitoring data is inaccurate, and the sampling precision is insufficient, leading to incorrect and delayed fault information detection.

According to media reports, monitoring data from centralized inverters at a power station in Inner Mongolia significantly deviated from actual power generation, with reported values 3% higher than the true output. 。

3. Junction Box

In photovoltaic power systems, a combiner box is used to minimize the number of cables connecting the solar PV array to the inverter. The components and functions within the combiner box include: wiring terminals, overcurrent protection devices, circuit breakers, surge protectors, grounding terminals, and intelligent data acquisition. Optional) Etc.

Common issues: Electrical short circuits, spontaneous combustion

As shown in the diagram, the installation company chose to save on structural steel by mounting three rows of photovoltaic modules on a flat rooftop—without installing connecting beams between the front and rear rows. Additionally, the stone piers used to secure the bottom of the支架 were too lightweight, and their shape was not rectangular, which would have helped distribute weight more effectively. Consequently, when the typhoon hit, the支架 simply lifted off. Photovoltaic支架 have poor corrosion resistance, which can easily lead to component detachment. Even if the components don’t actually fall, corroded支架 can still alter the tilt angle of the modules, resulting in reduced energy generation. Of course, when it comes to corrosion resistance, aluminum alloys far outperform steel. August Last month, a rooftop photovoltaic power station in Wuhan caught fire, leaving several large holes burned through the color-steel tile roof. Inside the factory building, numerous pieces of equipment were destroyed, resulting in substantial losses. The final investigation revealed that the incident was triggered when, due to improper construction or other factors, the insulation of a cable in a certain combiner box deteriorated and became insufficiently grounded. This issue was exacerbated by circulating currents and leakage currents, ultimately leading to complete insulation failure. As a result, the positive and negative cables inside the cable tray short-circuited and sparked, igniting the fire.

Case 2 Photovoltaic支架 have poor corrosion resistance, which can easily lead to component detachment. Even if the components don’t actually fall, corroded支架 can still alter the tilt angle of the modules, resulting in reduced energy generation. Of course, when it comes to corrosion resistance, aluminum alloys far outperform steel. May of the year Last month, a fire broke out at a mountainous photovoltaic power station. The local forestry department immediately ordered the suspension of grid-connected power generation and initiated a comprehensive risk assessment, which lasted for three months and resulted in losses amounting to millions. The final analysis revealed that the incident was caused by a cable in a certain combiner box being dragged and worn during construction. Over time, this damage led to insulation failure, causing a short circuit and arcing between the positive and negative cables—ultimately triggering the fire.

4. Photovoltaic Backsheets

The photovoltaic backsheet is the outermost layer on the backside of the PV cell, serving as a critical component. It not only provides encapsulation but also protects the PV cell from environmental factors, thereby ensuring the longevity of the solar module.

Frequently Asked Questions:

1. Yellowing

During the photovoltaic module lamination process, two layers of encapsulant film are used to bond the solar cells together, integrating them seamlessly with the glass front sheet and the backsheet. Typically, one of the two encapsulant films is designed to block short-wave ultraviolet light. Meanwhile, the backsheet itself provides protection against UV light in the 300nm–380nm range. While it exhibits a certain level of resistance to UV intensity, some backsheet materials still undergo yellowing when exposed to ultraviolet light. This degradation damages the molecular structure of the backsheet layer, reducing its overall performance. At the same time, the backsheet's reflectivity decreases, negatively impacting the module's overall power output.

2. Back panel bulge

Battery cells with hotspots, as well as areas where masking tape is applied, are prone to backsheet blistering—especially when these two locations overlap. This issue primarily arises due to high temperatures causing the materials to vaporize.

3. Bubbles under the backboard strips

The backsheet strips create a significant gradient between the busbars, and the installation staff failed to properly apply the EVA. Align the strip properly to create EVA. The filling wasn't done properly.

4. Backplate cracking

2012 This year, a photovoltaic power station in western China was successfully connected to the grid, with its brand-new modules gleaming brightly under the abundant sunlight. At the grid-connection ceremony, everyone’s eyes were filled with hope for the future.

2013 In the year, during random sampling inspections of the components, although no significant visual changes were observed with the naked eye, microscopic examination clearly revealed numerous microcracks on the surface of the backplate.

2016 This year, the market has started hearing more and more about systems equipped with only 4-5 This year, the components have begun showing backplate cracking—what started three years ago as microcracks has now evolved into longer, deeper macroscopic cracks. Many of these cracks have formed along the solder ribbons, posing a significant risk of unintended current leakage.

5. Photovoltaic Mounting Structures

As a critical component of photovoltaic power plants, the PV mounting structure supports the core power-generating units of the system. The choice of mounting structure directly impacts the operational safety, failure rate, and construction investment of the PV modules. Selecting the right PV mounting solution not only helps reduce project costs but also minimizes long-term maintenance expenses.

Frequently Asked Questions:

1. Poor wind resistance

Generally speaking, the entire photovoltaic power generation system requires robust mounting structures capable of withstanding typhoons, heavy rain, and other severe weather conditions. Theoretically, the maximum wind resistance capacity of solar-mounted structures is 216 km/h. Kilometers per Hours—solar tracking brackets can withstand winds up to 150 km/h at maximum. Kilometers per hour (for typhoons stronger than Category 13).

In practice, some brackets have encountered issues during selection or installation, leading to them being blown away by strong winds.

As shown in the diagram, the installation company opted to save on structural steel by mounting three rows of photovoltaic modules on a flat rooftop—without connecting beams between the front and rear rows. Additionally, the stone piers used to secure the bottom of the支架 were too lightweight, and their shape wasn’t rectangular, which would have helped distribute weight more effectively. As a result, when the typhoon struck, the支架 simply lifted off.

2.. Corrosion

Currently, the materials commonly used for solar mounting structures include hot-dip galvanized steel frames, stainless steel frames, and aluminum alloy brackets. Since solar panels are typically installed outdoors, these structures often face challenges such as exposure to sunlight and rain, leading to corrosion, rusting, and salt damage.

Photovoltaic支架抗腐蚀性差，容易导致组件坠落. Even if the components don’t actually fall, corroded支架 can still alter the tilt angle of the modules, reducing energy generation. Of course, when it comes to corrosion resistance, aluminum alloys far outperform steel.